1. Field of the Invention
The invention concerns a tightening frame for a tarpaulin, especially for mounting on a truck or truck trailer with a frame profile and an anchor profile that has, on its long edge facing the tarpaulin, a rounded-off foot, which can be inserted into one of optionally several rounded-off grooves of the frame profile or an intermediate profile connected to it and pivoted in it, in which case the anchor profile, by pivoting around its foot, enters the tightened state of the tarpaulin and a position parallel to the plane of the tarpaulin, and in which either the anchor profile or a weather-stripping profile connected to pivot with it has at least one receptacle for a weather strip.
2. Description of the Related Art
This type of tightening frame is disclosed in WO 01/35382 A. FIGS. 15 to 30, in particular, of this document show a variant in which the tightening conditions for the tarpaulin can be easily varied by a number of parallel ledges, in which the frame is intrinsically secured in the rest state by the geometric dimensions, i.e., without additional fastenings, [made secure] against undesired opening. However, the following must be said concerning this:
The upper weatherstrip profile is exposed by the tension of the tarpaulin to a counterclockwise torque, in FIG. 30, around the suspension point on the frame profile. This would lead to a reduction in tension of the tarpaulin, but the weatherstrip profile, due to its edge extending upward and toward the plane of the frame (not shown), cannot be rotated so that selected ledges remain fixed on the notch of the frame profile.
The situation is similar on the lower edge of the tarpaulin: tension of the tarpaulin exposes the weatherstrip profile to a clockwise torque around its pseudojoint (roughly in the center of the profile, formed by the end of the protruding part of the frame profile). Movement in the clockwise direction around this point, however, is hampered by the tarpaulin profile, on which the end of the weatherstrip profile away from the tarpaulin is suspended. This tightening profile is also exposed to a clockwise torque and, on the other hand, is supported on the frame (not shown) with its widely protruding end. However elegant this solution appears to be at first glance, it is problematic in practice: Because of the far protruding arm of the frame profile on whose ends the pivot axes of the weatherstrip profile are formed as pseudoaxes, large bending moments and bending stresses occur that must be tolerated over the entire service life of the profile even during rough operation without permanent deformation. To this, it must be added that the entire tensile force of the tarpaulin acts on the outermost ends of these arms, which makes an overload very easily possible during application of the tarpaulin by the tightening profile.
Finally, the intrinsic security of the tightening frame depends exclusively on contact of the outermost edges of the weatherstrip profile or tightening profile on the components that are not part of the frame, which, on the one hand, leads to high bending stresses and the tendency toward plastic deformations or rupture because of the absence of any other support of this profile and, on the other hand, requires corresponding design of the components to carry the frame.
The design of the profile is not appropriate for reliably maintaining intrinsic security in the case of vibrations, or in the case of penetration and freezing of water in the gaps between the frame or the frame's surroundings and the weatherstrip profile or tightening profile, inevitably causing opening of the tightening frame.
Another drawback is that discrete snap-in possibilities into the profile acting on the tarpaulin are only provided on the tightening side opposite the tightener or tightening device. Moreover, the profile separates where no tightening is present, so that handling of the tarpaulin or profile by a single person is almost impossible.
Another type of frame is disclosed in EP 0 495 688 A 1 and in a variant that comes closest to the invention, according to FIGS. 4a and 4b of this document. However, these figures show a tightening device for a tarpaulin in which, even in the end position, a torque always remains in the opening direction of the tightening device because of tension in the tightened tarpaulin; it is therefore not intrinsically secure.
Even during the use of fixed poster walls or the like, this tightening device must always be additionally secured, which occurs in the depicted case by an elastic snap connection. This tendency for opening of the tightening device also exists when the two tightening frames are not arranged, as disclosed, normal [at a normal angle] to the actual tarpaulin surface, but run in the plane of the tarpaulin, since even then the connection or deflection edges that are necessarily provided cause torque in the opening direction. In addition, the device known from EP 0495688 A1 offers no possibility for easy and simple adaptation of tightening or adjustments to different tarpaulin sizes, as can be the case, for example, during expansion of the fabric exposed to tension for a longer time. For example, during adjustment of tarpaulin tightening on the frame, the tightening profile must be threaded around a different weatherstrip groove.
In comparison with this, the invention seeks to devise a so-called intrinsically secure tightening device, which is understood to mean a device that is held in the closed position by the tension in the tarpaulin. The fact that in different applications, such as in the tarpaulins of trucks or the like, additional fastening can be provided as an additional means of security [tightening], changes nothing in the objective of this intrinsic security.
U.S. Pat. No. 5,893,227 A discloses a tightening frame similar to the one in the aforementioned documents, but in which the possibility of simple and rapid adaptation to alter tightening conditions can be achieved due to the presence of several groove-like recesses (these can also be called hook-like protrusions). The problem of intrinsic security, however, also fully exists here and is solved by an outer profile that is snapped over the entire frame so that tilting away of the actual tarpaulin holder in the opening direction is prevented. The tightening devices in this tightening frame also lie in a plane that runs normal to the plane of the tarpaulin and, unlike EP 0 495 688 A 1, an arrangement within or parallel to the plane of the tarpaulin is not possible here, since securing with the outer profile no longer functions and the tightening frame can no longer be used.